1. Field of the Invention
This invention relates a disk storage system, and more particularly to a disk storage system having information of defects relating to a disk.
2. Discussion of the Background
A typical construction for an information processing system provided with a disk system, for instance a magnetic disk system, is shown in FIG. 1. In FIG. 1, a magnetic disk system 30 is connected with a computer (host system) 40 through an input/output control system 50. Input/output control system 50 governs the data input/output of computer 40 and magnetic disk system 30 by controlling magnetic disk system 30 in response to requests from computer 40. A terminal 60 is connected to computer 40.
Magnetic disk system 30 includes disk drive (hard disk drive) 32 in which magnetic disk (hard disk) 31 as a memory medium is installed and disk controller (hard disk controller) 33 which controls disk drive 32. Disk drive 32 drives magnetic disk 31 in its operable state.
In the system in FIG. 1, when, for instance, a request for disk formatting is made to computer 40 from terminal 60, computer 40 causes the formatting of magnetic disk 31 to be executed by controlling disk controller 33 in magnetic disk system 30 via input/output-control system 50. When there are defects on magnetic disk 31, at disk formatting, disk controller 33 detects the defects on magnetic disk 31, as shown by symbol D in FIG. 2. Then, `defect-related` information, which includes the disk addresses of these defects, is written to (recorded in) map table 71 maintained in a specified recording area (here, the final cylinder area of the same head) of the same magnetic disk 31, and formatting is continued. The recording area of magnetic disk 31 other than map table 71 is used as user area
The defect-related information written to map table of magnetic disk 31 can be read into computer 40 by using the disk controller 33 via input/output control system 50, for instance, in response to a `defect-related` information read request from terminal 60. This `defect-related` information is used for the preservation of magnetic disk system 30.
The prior art is designed in the above way to record defect-related information in a map table which is reserved in a specified area of the disk. For this reason, there was the problem that, when a defect occurred in the map table, this disk system could not be used. There is also the problem that when the disk content is damaged there is a risk of the `defect-related` information also being damaged at the same time. Furthermore, there is the problem that when the input/output control system provided between the computer and the disk system is not correct the map table could not be accessed.